Why Nuclear Fusion Will Never Work

I’ve been trying to get my head around Nuclear Fusion recently. Advocates suggest it will solve virtually every problem ever conceived if they ever get it up and running. I remain unconvinced, yet they still keep asking Governments all over the world for huge buckets of money, on the promise of limitless, ‘clean’, energy.

From the top then, for those who weren’t concentrating during nuclear physics at High School.

Atoms, the stuff all matter is made from, are made of a nucleus and orbitting electrons. In the nucleus there are always protons, and usually neutrons. The exception is Hydrogen, the simplest atom we know, which is often just one proton and an orbiting electron. The number of protons in an atom is what governs the type of atom it is; 1 proton for Hydrogen, 2 for Helium, 79 for Gold and 118 for the largest ever recorded atom, Ununoctium, of which 3 atoms have ever been recorded. This would have been manufactured as a part of some sort of heavy ion collision experiment. It would have been a short but spectacular life for an atom.

So, protons govern the type of atom, but also in the nucleus are neutrons, which don’t contribute much at all, except a bit of mass. Neutrons occur at about the same frequency as protons in a nucleus, but sometimes a couple more neutrons might be present. Hydrogen for example, can have none, one (deuterium) or two (tritium) neutrons in its nucleus. The mass number on the periodic table describes how frequently there are more neutrons. Mass number for hydrogen is 1.008, which means if you have a huge bucket of hydrogen atoms, their average mass will be 1.008 protons, the extra .008 describes atoms with the odd extra protons. 99.98% of all hydrogen atoms (and there are a LOT of them) are Hydrogen with one neutron though (H1).

Nuclear energy is all about the interaction of nuclei. There are 2 basic types of nuclear energy, fission (splitting atoms) or fusion (joining atoms together). Imagining watches as nuclei for a moment, which do you think is easier? Banging them together to see what comes out; or joining them together to make new things. Yep, smashing them open and taking the energy is heaps easier.

Fission is the ‘dirty’ nuclear that everyone knows. France has a huge nuclear industry, running 59 power plants. It produces massive amounts of energy and is pretty safe, considering how risky the concept is. There are ongoing concerns about how to store the waste though, which is one of the most poisonous substances known to man. Summarising; fission is a known quantity, it makes stacks of energy but the waste is a problem.

However, should we ever get a fusion industry going (and I strongly doubt it) there won’t be concerns about waste as the waste products are quite benign. Atoms are much more dangerous the larger their nucleus; bigger atoms can decay more easily which releases radiation. Fission uses huge uranium and plutonium atoms; fusion uses hydrogen and produces lithium.

The energy out of fusion reactions is extraordinary. Sadly, the best way to compare the 2 is with nuclear bombs. The most powerful fission bomb ever built is the equivalent to about 700,000 tonnes (700 kT) of TNT; some fusion bombs have been recorded at up to 15-50,000 kT of TNT. It’s a totally different ball park.

So, how does fusion work and why aren’t we using it everywhere? The fusion reaction is what powers our sun. There’s stacks of hydrogen in there, at incredible heat and pressure, with nuclei banging into each other continuously and emitting all of the energy we feel on earth. It’s good stuff. The lefty in me suggests that we could power our whole country from this fusion energy if we invested heavily in solar, but that’s another story. The real game in nuclear is creating and controlling the fusion reaction on earth.

It’s not really ‘controlled’ in the sun, which is why it works. You put enough hydrogen in one place and the gravitational pull of all that matter will squash it into the right conditions for fusion. It happens all over the universe in virtually every point of light you can see in the night sky.

The difficulty is in making a small, controllable, sun in a laboratory on Earth somewhere. This requires higher temperatures than the sun, because we can’t replicate the pressure in the sun as well. The goal of fusion is to bang hot nuclei together to make new nuclei, and harvest the energy that is created.

So, ideally it would work like this; a stack of hydrogen is ‘ignited’ to ‘plasma’ temperatures. Plasma is the 4th state of matter, in the same series as solids, liquids and gas. Imagine water; the solid is ice which occurs at zero degC. This melts and is a liquid from 0-100 degC, then over 100 it becomes a gas. In all cases the atoms are unchanged, but moving faster as the temperature goes up. But what if you wind the temperature up a lot, say from 100 degC to 100,000 degC. Now we’re getting near plasma temperatures.

Like liquid/gas phase change, the temperature (and pressure, they’re linked) that a substance becomes a plasma varies depending on the substance. In a liquid all the atoms are touching each other, but free to move around. A gas is when the atoms are no longer touching and moving around everywhere inside their vessel. Plasma though is once it is hot enough for the electrons to actually leave the atom and float around independently so creating a ‘soup’ of atomic particles; free electrons and nuclei all flying around together.

The ignition temperature can be achieved through a number of means; most commonly by applying a very strong magnetic field and recently using high-energy lasers. In isolation this is not very difficult, but keeping the reaction going is. What sort of material would you use to put a sun inside? Magnetic fields are the answer and current fusion experiments in a tokamak involve creating a plasma and containing it within a donut shaped magnetic field. In this way they can keep it moving around in circles without touching anything, which it would most certainly destroy.

Because the larger the atom is, the higher the energy required to cause collisions and start a plasma, most experiments are focussed on the lightest atoms; the hydrogen family. But to make the collisions more effective they concentrate on deuterium and tritium as the extra nuclei make the atoms a tiny bit bigger and heavier. So the reaction is run at temperatures to make hydrogen fuse; different atoms would require higher temperatures. And here is the problem.

As the reaction continues the hydrogen atoms involved in collisions become other things; Helium and Lithium in particular. The reaction is hot enough to fuse hydrogen, but nothing else, so as the heavier atoms are formed, it pollutes the reaction; in a very similar way to exhaust in a car. The moment the hydrogen atoms release their energy and become something else they go from helping the reaction to hindering it. To keep the reaction going, these new atoms need to be removed.

How on Earth can that be done? I doubt it can be, and I will eat a large hat if they crack it during our lifetime. Imagine a ‘gas’ cloud at 1 million degrees C. In it, spread randomly throughout are 2 different types of atoms. You need to keep one type in there and stinking hot; the other type needs to be removed because it’s wrecking the reaction.

If it is ever achieved, it will be achieved using oscillating magnetic fields which can exploit the minute mass difference of the 2 different atoms. I’ve been wondering if it is possible in a circulating fluid where there is no separation of reactants and pollutants; maybe they’ll end up with some sort of reciporocating device like a car engine, or a through-put device like a gas turbine. In either case it’s hard.

Despite all this, fusion research continues to tick along. At the moment the ITER guys are scouring the globe for forward looking governments willing to cough up for something that is unlikely to pay back during our lifetime. Current proposals require something like $50billion to build a new test bed reactor that they hope to have running by 2018. There are currently no designs or plans for demonstration reactors, let alone widespread grid connection. But like I said, if they crack it, a lot of problems will disappear.

Nerds all over the world live in hope, but personally, I’ve given up, and will concentrate on harnessing the fusion reaction that is already going and will be for a very long time to come.

EB

Advertisements

About evcricket

Extreme gardener, engineer and bird nerd.
This entry was posted in Uncategorized and tagged , , , . Bookmark the permalink.

20 Responses to Why Nuclear Fusion Will Never Work

  1. Rober2D2 says:

    I have just seen a documentary about the current three main investigations over fussion: ITER, NIF and the Z-Machine in Sandia Labs. My conclusion: This is simply too complex to work. It’s not very scientifc, I know, but the engineer in me tells that something that depends on such perfection and precission will never work. And if it works, it will be so expensive that we won’t use it. Any fail, even the slightest one, and fussion won’t work.
    But there is even a bigger challenge for nuclear fussion. Once solar and wind are more extended, and customers know what is energy independence … Will they buy fussion energy from big corporations? There is a big chance that fussion is achieved in a time when it is no longer needed.

  2. Wizardrous says:

    Besides all the other arguments presented, I would like to point out that it being unlikely to be achieved within our lifetime is a poor basis for an opinion. Even if that were so, which I don’t particularly agree it is, it is necessary for the overall good of the human race to think about future generations. It seems selfish to think it would be a better idea to throw away that idea and spend the money on current problems, while only creating bigger problems for future generations, rather than investing in technologies that will allow the human race to live on for millennia. With nuclear fusion the possibilities for our species are endless; we could even use it in the distant future to power spacecraft that will carry us to other solar systems, which simple solar power could not achieve.

    • Maury Markowitz says:

      But the problem is that fusion is unlikely to ever “work” in the economic sense. It is highly likely it will work in the *engineering* sense, but that’s very different. After all, MythBusters got a lead balloon to fly, but we aren’t crossing the pond in the Lead Zeppelin, and never will.

      The basic problem is this: fusion energy is *extremely* diffuse. Even at its maximum operating conditions, a reactor like ITER’s internals are best described as a “very good vacuum”. NIF’s fuel is denser than lead, but only at the center of an enormous chamber, so the average density is even lower.

      So this means that in order to make machines that put out useful amounts of power, they need to be *enormous*. And not just big, but *fantastically* complicated too. Orders of magnitude more complicated than a fission reactor for instance, which is more complicated than, say, a natural gas turbine.

      Enormous, fantastically complicated devices cost lots and lots of of money. A commercial fusion plant will almost certainly be the most expensive thing ever built.

      The cost of electricity provided by any large power source like this is largely a function of the interest payments on its construction. So if a fusion plant costs, say, 10 times as much as a fission one of the same power, then the electricity will cost 10 times as much. And if that is the case, no one will ever build one.

      It is really that simple. If you would like more intellectual rigour, and even some numbers and calculators to play with, look for the link I provided below. This isn’t rocket science, you can do the basic math yourself.

      We also have to consider that fusion is definitely not the only way to provide, as you put it, “possibilities for our species [that] are endless”. After all, wind and solar power will be available just as long as the Earth is.

      So if I can build, for instance, a wind turbine and a week of battery backup, thereby providing uninterrupted power, and I can do that for less than the cost of a fusion plant, I’m not going to build a fusion plant.

      Right?

      And that’s the problem with fusion.

    • BINGO, except for the generations thing because Turritopsis Nutricula.

  3. MB says:

    Dear Sir,

    You seem to be worried about the He ash build up in the reactor core. But this problem is dealt with in the same way as a car engine works. Burnt gas products from the reactor are continuously flushed and replaced with new D, T fuel mixture. The exhausted gas D, T, He is pumped from the core through a pumped divertor in the bottom of the fusion reactor torus. It is a proven concept.

    And nuclear fusion is not as well funded as you might think, in spite of its continual progress. For example, the US spent approximately 1000 times more on the war in Afghanistan alone, than the whole world will spend on ITER.

    Cheers.
    An optimistic Nuclear Fusion Scientist.

    • Maury Markowitz says:

      “The exhausted gas D, T, He is pumped from the core through a pumped divertor in the bottom of the fusion reactor torus. It is a proven concept”

      That’s the plan, certainly, and has been since the 1950s. And certainly existing diverters are very useful for reducing wall loses. But is anyone actually *doing* on-line pump-out and ash removal in an operational reactor?

  4. Maury Markowitz says:

    Old pst I know, but some of my thoughts on this:

    http://matter2energy.wordpress.com/2012/10/26/why-fusion-will-never-happen/

  5. Natty Bummpo says:

    While we should never, ever turn a blind eye to any facet of science and learning, as Monsignor Evcricket and others above enumerate, Isochroma makes good points about overpopulation being the looming, overarching cause of ALL our maladies. Even a free, clean, safe source of energy as fusion won’t curb fishless oceans, vanishing farm and wetlands, declining quality of life, immigration woes, the entire South and Central American rain forest, what Dr. Helen Caldicott calls “the lungs of the earth,” Amazon dot gone by 2035 at present rates of destruction. Nor will fusion prevent future wars over not oil, but copper, fresh water. “Smart growth” without curbing overpopulation just means turning suburbia into Queens, NY.

    Fusion and all research, all learning, should never be impeded, but must be accompanied by reversing population growth. Nearly a third of a billion people in the US now, 7.1 billion globally is hell enough.
    Radio telescopes have revealed no elements unknown on earth, and Stephen Hawking is not the first to suggest that any intelligent life would likely see us as little more than slave labor or food. Witness how Europeans treated other peoples throughout history.

    And yet, exploring the cosmos is part of who we are. But we need to triage, balance. We still know so laughably little about the oceans, fount of all life.

    This may seem off topic to some, but as Isochroma suggests, until we curb overpopulation, the wonder of fusion will only power business and destruction as usual.

    Fusion and other research must accompany attention to the basics, like ending meat and dairy consumption. Fully half of all domestic fresh water is used in meat production. Women in nations with the highest per capita diary consumption have the highest rates of osteoporosis. As they say, “There’s a slice of veal in every glass of milk.” And according to the UN, meat production contributes more greenhouse gas than all the world’s cars, trucks, busses, trains, planes, ships combined.

    So, as we continue to research fusion, the cosmos, we should spend a wee bit of intellectual capital helping the populace at large realize that we’re all of the same stardust, DNA, that the baby factory doesn’t need to run three shifts a day, seven days a week, that everyone must be born now. We should instead invite humanity to wonder if you’re not born in 2013, if you might still be born in 2812, 8312, 13612. We need to pressure the Pope and other religious leaders to the take the ethical high ground of encourage adoption over breeding; change our tax codes to encourage adoption, tax breaks for those having one or none, else fusion’ll only give the already out of control juggernaut ever more power.

  6. peter says:

    Another key issue is time. We are way over sustainable levels of carbon concentrations in the atmosphere and oceans and need to scale up renewable fast. Peak oil is here. Utopian red herrings like ITER keep us distracted and hamstrung in hopeless inaction while this time bomb is ticking. Even if fusion worked tomorrow it would take far too long to build enough expensive, massive and centralised devices to make any difference in our climate and energy conundrums.

  7. Steven Corbett says:

    isochroma. The amusing this is, with your attitude, a lot of the technological developments that we take for granted today would not even exist, cause the funding would have seemed too high for you. Though granted nuclear fission reactors owes a lot to war and the money spent on research there, but its still research money.

  8. Look up Dr Lerner for a design that has far more promise!!!!

    • evcricket says:

      It does look interesting Patrick, but I wouldn’t mind seeing a few more published papers.
      http://www.lawrencevilleplasmaphysics.com/

      Working in energy I have seen many, many different examples similar to this; self-promoted revolutionary energy projects that consist of a website and a few interesting ideas. One of them might actually work, but I’m sceptical for the moment.

  9. jack says:

    There are many designs for what to build after ITER:

    http://en.wikipedia.org/wiki/DEMO

    Here is an honest account of the scale of the energy crisis, the need for fusion and the justification of the cost of ITER:

    International collaboration makes these processes slow.

    Huge challenges need a certain amount of money spending – often dwarfed by other expenditures.

    Don’t blame the tiny science funding budget for huge gaps in welfare expenditure; blame defense and lack of tax on big business

  10. isochroma says:

    Let the People vote on what, when and how much. The scientists and corporations have their own financial interests at heart, not the peoples’. They want the fusion program to be and endless gravy-train feeding trough – as it has been for so many decades so far.

    My hope is not to see those employed on the blackhole gravy-train unemployed, but to create for them better jobs. Jobs with a real future. Ones that undo the real causes of the problems we face today, rather than jobs trying to keep the monstrosity chugging along.

    While they’re chasing stars and big cheques, there is no decent program in place for demand reduction. That is, population control and lots of other programs that could have been funded had the billions of dollars not been flushed down the fusion-drain.

    Whether fusion eventually works or not isn’t even important. There’s tons of other, hard limits to the ever-expanding human infection that is destroying Earth. Fusion is another last-ditch attempt to keep the whole death-machine grinding on while no serious effort is being made to reduce demand.

    Furthermore, fusion is not a substitute for oil or coal, both of which are used in ways qualitatively different from the electricity produced by fusion. Even if fusion energy was free, it won’t stop Business as Usual from running off its self-made cliff, because the entire program is a runaway train.

    Building an internal-combustion engine for a runaway train so as not to lose velocity as the steam-engine gives out is what that program is all about. They don’t care that the tracks end not far up ahead. They want political kickbacks and money today.

    Those who say the train ought to be slowed down, allowed to slow down, and especially the nuts who insist on developing brakes to stop it are cut out from the dialogue. They are dangerous to the short-term program.

    Building more engines or more efficient engines will only propel such a mess faster toward the inevitable cliff of total resource depletion and further overpopulation. The phosphates are running out. Copper is running out. Many other unsubstitutable minerals will be uneconomic to mine if not entirely depleted in the next fifty years. The biologic capital of vast ecosystems is almost run out already. In fifty years most of the ocean’s current fish population is projected to be gone.

    The only thing that would save them is when it costs too much to fuel boats which ‘harvest’ them wholesale with the too-cheap fossil-fuel energy. When fishing goes back to hand- and wind-powered sources, its scope and ability to pillage will be vastly reduced.

    To sum up, the billions spent on fusion could better be spent re-adapting people to the future world. A world of ever-declining materials upon which we depend. A world of painful readjustments at all levels. Whether fusion works or doesn’t isn’t going to change the picture much for the better, but the money, time and materials lost to its alluring fantasy can never be recovered, and certainly not the precious time which is ever ticking toward the moment of collapse – the long drawn-out phase in which an overproliferated, destructive species will be forced by external circumstances into the most terrible of circumstances – both for itself and the environement it will continue to the best of its ability to pillage.

    The take-home message is that only when humans are too energetically weak to pillage will the rape stop. History bears this out, and so too will the future. It’s just another retelling of the tragedy of the commons.

    • Ian Morill says:

      Hi, this is specifically in reply to ‘isochroma’ At last i’ve finally read something from someone who seems to be living in the real world . I think the human race is more clearly defined by the words ‘naive’, ‘deluded’, ‘arrogant’, and ‘egotistical’ rather than having a ‘big brain’ or ’empathy’ or ‘compassion’. We don’t use those abilities too well do we. But to think we can do better than the very set of circumstances that brought about our existence is truly naive,deluded, arrogant and egotistical. It might seem like a slow journey to oblivion but in historical terms it’s like a blink of an eye. It hasn’t been progress, rather than a progression towards extinction. We’re actually going to be able to document our own demise. now that’s impressive. I’m sure a reality show will be devised to complete the process. Wake up, we’ve always convinced ourselves that we’re making things better while all the time making things worse.

  11. ET says:

    I just saw this after someone revived the climate thread on chockstone… and like to point out that fusion is already routinely obtained in the lab (i.e. I don’t think removal of contaminants is a serious issue anymore…)

    Before I continue, I’m going to state clearly that I do not specialize in nuclear fusion, but have some familiarity with a few of the devices. Devices like Inertial electrostatic confinement (IEC) chambers, tokamaks, stellerators, etc all are capable of sustaining fusion reactions for long periods. The biggest issue for the ITER project is to get commercial volumes of net energy out of the reaction (you need to invest a huge amount of energy to initiate and sustain the reaction).

    My history maybe a bit off, but I THINK the break even point (energy in = energy out) had been achieved in 1998 in either the JT-60 or JET tokamaks. To get more net energy out however, the device needs to be scaled up as energy losses occurs at the walls of the device (hot ions hit the wall and become cold). Scaling up the device minimizes the surface area to volume ratio thus increasing its efficiency (reactions occurs in volume, losses occurs at walls). There are lots of other issues as well before the technology can be commercialized such as material to withstand long term neutron bombardment, suitable material at point where hot ions are injected (not the walls themselves, they shouldn’t get that hot provided the magnets are working and the hotter ions are mainly confined towards the center of the tokamak…) as well as how to extract energy from hot neutrons among other things (I think the leading contender in that aspect is using liquid sodium, that doubles up as a way of breeding tritium at the same time).

    All that said, yes ITER has wasted tonnes of money and it has gone waaaay over budget (there’s a lot of bureaucracy and politics involved… I believe the story goes that it took involved parties ~20 years of negotiations to decide where to build the damn thing)… but that can be said for a lot larger projects and at least a lot of the key concepts for the project has already been proven.

    • evcricket says:

      Nice one. Some intellectual rigour. I too make no claims as to nuclear energy skills, clearly it seems…

      Most of my post came from discussions with a mate who has worked at CERN and some of the other accelerators from around the world. I’d forgotten that materials were the limitation, also heat reclamation.

      Cheers.

      Funny too that Rod revived the post. I think he was fishing to see if I’m still around. Too ashamed to show my face at Chocky at the moment, haven’t tied in since March.

      Ev

  12. isochroma says:

    ITER is big alright. ITER is a big fatass theft of taxpayer dollars, just like every single other publicly-funded fusion ‘program’.

    Each one is a huge fatass black hole sucking down taxpayer dollars that could have been spent on better things than giant corporate welfare programs. Like housing for the people, like guaranteed annual income, like population reduction, like environmental protection.

    It is time to halt these boondoggles before they suck up more precious taxpayer dollars which are so desperately needed to help the ever-growing underclass of people living in poverty.

    The taxpayer is being told to starve so these trojan programs can continue to leech away their livelihoods. Witness today’s ‘Austerity’ programs beginning to spread through Europe and soon everywhere… there will be no money for your children or retirement as the elites are spending every Country into bankrupcy with their Wars and so-called Defense Spending and spending on toxic Fission and blackhole Fusion ‘technologies’.

    From its inception to today, fusion has been a gigantic blackhole welfare program for the rich corporations and their scientistic employees with the starving taxpayer footing the bill.

    No more. Its time to end all public funding for these so-called ‘energy’ programs. If there’s money in it let the so-called ‘Free Market’ fund it. After all, those richie private investors already have trillions floating around that they don’t know what to do with, why don’t they risk their own assets and asses instead of making the taxpayer the victim? Hypocrisy, hypocrisy, hypocrisy.

    • evcricket says:

      I’ve decided to let this one through. I’d prefer a bit more rigour from my commenters though. Why is it a ‘huge fatass black hole’? If they crack it next year, surely it will appear to be a good investment? How are you proposing to determine which energy programs get funded and which ones dont? Are you in favour of ANY Government spending in technology? Or any spending at all?

      Be mindful that markets are sometimes not the best mechanism for picking up promising, early stage technologies. A lot of people will argue that there will always be a role for Government in this area. Consider your position carefully here. Pulling the pin on energy investment by Government could mean we all miss out. But, there’s a risk/reward mechanism at work here, and it’s your choice how you determine if a risk is good value or not.

      EvC

      • Maury Markowitz says:

        Why is it a ‘huge fatass black hole’? If they crack it next year, surely it will appear to be a good investment?

        Probably not. The problem is not only technical, but economic as well. Even if ITER were to hit 10x power output ratio tomorrow, it would generate power at many times the price of existing options. The complexity is too high, the density too low.

        We may be 50 years from a generator. But we’re infinity years from a practical one.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s